Pastern OA study links frequent concurrent ligament injury in horses
Bottom line
Straight sesamoidean ligament desmopathy appears to be a common concurrent finding in horses with proximal interphalangeal joint osteoarthritis, according to a new retrospective study in Equine Veterinary Journal. Reviewing 58 horses with pastern joint osteoarthritis, investigators found that 46.7% also had straight sesamoidean ligament desmopathy, and the severity of the ligament lesion was positively associated with the severity of the osteoarthritis. The authors say the findings support more deliberate soft tissue evaluation of the pastern region, especially in horses with advanced radiographic changes or cases that aren't responding as expected to treatment. (beva.onlinelibrary.wiley.com)
Why it matters: For equine veterinarians, the study adds to a growing reminder that pastern lameness may not be explained by radiographic osteoarthritis alone. The straight sesamoidean ligament helps stabilize the proximal interphalangeal joint, and prior literature has identified straight distal sesamoidean ligament injury as a recognized cause of distal limb lameness in horses. Standard workups for pastern osteoarthritis often emphasize bony change, but these findings suggest that concurrent soft tissue injury may be contributing to pain, case chronicity, or an incomplete response to therapy, making ultrasonography or advanced imaging more relevant in selected horses. (beva.onlinelibrary.wiley.com)
What to watch: Whether this association changes routine imaging protocols for horses with pastern osteoarthritis, and whether prospective studies clarify if the ligament injury is a driver of disease, a consequence of altered biomechanics, or both. (beva.onlinelibrary.wiley.com)
Key facts
- Study type
- Retrospective study
- Journal
- Equine Veterinary Journal
- Sample size
- 58 horses with proximal interphalangeal joint osteoarthritis
- Concurrent finding
- 46.7% also had straight sesamoidean ligament desmopathy
- Association
- Ligament lesion severity was positively associated with osteoarthritis severity
- Clinical takeaway
- Authors recommend more deliberate soft tissue evaluation of the pastern region
- Higher-yield cases
- Advanced radiographic changes or cases not responding as expected to treatment
A new Equine Veterinary Journal study is putting more attention on the soft tissue side of pastern disease in horses. In a retrospective review of 58 horses with proximal interphalangeal joint osteoarthritis, nearly half, 46.7%, were also diagnosed with straight sesamoidean ligament desmopathy, with a significant positive correlation between the severity of the two conditions. The takeaway is practical: horses with pastern osteoarthritis may also be carrying clinically relevant ligament injury that isn't captured by radiographs alone. (beva.onlinelibrary.wiley.com)
That matters because proximal interphalangeal joint osteoarthritis, often recognized clinically as pastern ringbone, is already a familiar cause of chronic lameness and reduced performance. Standard evaluation tends to center on periarticular new bone formation, joint remodeling, and other radiographic signs of osteoarthritis. But equine clinicians have long known that distal limb lameness can involve overlapping structures, and that localization by diagnostic analgesia doesn't always cleanly separate joint pain from nearby soft tissue pathology. (merckvetmanual.com)
The new report builds on that broader diagnostic picture by highlighting the straight sesamoidean ligament, one of the stabilizing structures associated with the pastern region. Earlier work has described straight distal sesamoidean ligament desmitis as a recognized source of distal limb lameness, and more recent reports on pastern-region ligament injuries have noted that the straight sesamoidean ligament works alongside the palmar and plantar ligaments to resist hyperextension of the proximal interphalangeal joint. In that context, finding a relatively high rate of concurrent desmopathy in horses with pastern osteoarthritis is biologically plausible, even if the retrospective design can't establish cause and effect. (pubmed.ncbi.nlm.nih.gov)
Outside commentary specific to this paper was limited in public sources, but the broader equine imaging literature points in the same direction: soft tissue assessment can be important when lameness seems disproportionate to radiographic findings or when treatment response is poor. AAEP educational material notes that pastern ultrasonography is indicated in selected horses, and Merck Veterinary Manual guidance across equine lameness conditions similarly emphasizes combining radiography with ultrasonography, and using MRI when needed, to identify concurrent soft tissue and osseous disease. That's consistent with the study authors' recommendation to look more closely at the pastern soft tissues in advanced or refractory cases. (aaep.org)
Why it matters: For veterinary professionals, this study may shift the threshold for imaging beyond radiographs in horses with proximal interphalangeal joint osteoarthritis. If nearly half of affected horses in this cohort also had straight sesamoidean ligament desmopathy, then some cases labeled as straightforward osteoarthritis may actually be mixed joint-and-ligament disease. That has implications for prognosis, client communication with pet parents, rehabilitation planning, and treatment selection, particularly when horses fail to improve after intra-articular therapy, shoeing changes, or routine rest and anti-inflammatory management. The study doesn't prove that treating the ligament lesion separately improves outcomes, but it does suggest clinicians may miss part of the problem if the workup stops at bony change. (beva.onlinelibrary.wiley.com)
There are also some important limitations. This was a retrospective study, so the population likely reflects referral and imaging biases, and the available abstract doesn't provide the full breakdown of case selection, imaging criteria, or outcome data. Publicly available sources also didn't yield a press release or formal expert reaction tied directly to publication of this paper. Even so, the central finding is clinically useful because it reinforces a pattern equine practitioners already encounter: distal limb lameness is often multifactorial, and advanced osteoarthritis may coexist with meaningful soft tissue pathology. (beva.onlinelibrary.wiley.com)
What to watch: The next step is whether prospective studies can show how often concurrent straight sesamoidean ligament injury changes case management or prognosis, and whether equine practices begin using pastern ultrasonography more routinely in horses with advanced proximal interphalangeal joint osteoarthritis or an unexpectedly poor response to treatment. (beva.onlinelibrary.wiley.com)